The present invention relates to a base for a wide mouth blow-molded plastic container, and more particularly, the present invention relates to a multi-functional base structure which enables use of the container in hot-fill, as well as pasteurization/retort processing.
Plastic blow-molded containers, particularly those molded of PET, have been utilized in hot fill applications where the container is filled with a liquid product heated to a temperature in excess of 180xc2x0 F. (82xc2x0 C.), capped immediately after filling, and allowed to cool to ambient temperatures. Plastic blow-molded containers have also been utilized in pasteurization/retort processes where a filled and sealed container is subjected to thermal processing and is then cooled to ambient temperatures. In both cases, the containers are typically provided with vacuum absorption panels to accommodate volumetric changes in the container as the contents of the sealed container are heated and/or as the contents cool within the sealed container.
Co-pending U.S. patent application Ser. No. 09/601,088 filed on Jul. 27, 2000 assigned to Graham Packaging Company, L.P. discloses a hot-fillable and retortable plastic wide-mouth blow-molded container having a sidewall with a pair of flex panels. The above referenced ""088 application corresponds to International Application No. PCT/US00/05118 published as WO-00/51895.
Co-pending International Application No. PCT/US00/31834 also assigned to Graham Packaging Company, L.P. discloses a pasteurizable wide-mouth container having a novel base.
Other plastic wide-mouth containers having paneled sidewalls are disclosed in U.S. Pat. No. 5,887,739 issued to Prevot et al.; U.S. Pat. No. 5,261,544 issued to Weaver, Jr.; and U.S. Pat. No. 5,092,474 issued to Leigner. A pasteurizable plastic container having paneled sidewalls and a narrow neck finish is disclosed by U.S. Pat. No. 5,908,128 issued to Krishnakumar et al.
Containers having non-paneled sidewalls and yieldable endwall structures are disclosed in U.S. Pat. Nos. 4,642,968, 4,667,454 and 4,880,129 issued to McHenry et al.; U.S. Pat. No. 5,217,737 issued to Gygax et al.; U.S. Pat. No. 5,234,126 issued to Jonas et al.; U.S. Pat. No. 4,381,061 issued to Cerny et al.; U.S. Pat. No. 4,125,632 issued to Vosti et al.; and U.S. Pat No. 3,409,167 issued to Blanchard. The above cited U.S. patents disclose containers having various base structures.
The structure of a so-called footed base is disclosed, in general, in U.S. Pat. No. 4,355,728 issued to Yoshino et al.; U.S. Pat. No. 5,713,480 issued to Petre et al.; U.S. Pat. No. 3,727,783 issued to Carmichael; U.S. Pat. No. 4,318,489 issued to Snyder et al.; U.S. Pat. No. 5,133,468 issued to Brunson et al.; U.S. Pat. No. 5,024,340 issued to Alberghini et al.; U.S. Pat. No. 3,935,955 issued to Das; U.S. Pat. Nos. 4,892,205, 4,867,323 and Re. No. 35,140 issued to Powers et al.; and U.S. Pat. No. 5,785,197 issued to Slat.
U.S. Pat. No. 4,321,483 issued to Dechenne et al. discloses a base having a slightly angled annular surface and a central conical projection; and U.S. Pat. No. 4,386,701 issued to Galer discloses a blow molded plastic drum having a base which is designed to stack efficiently with the lid of a like drum.
While the above referenced containers and base structures may function satisfactorily for their intended purposes, there is a need for a plastic, wide-mouth, blow-molded container which is particularly suited for packaging a variety of viscous and other food products and which has a novel base structure that enables the container to be utilized in hot-fill and pasteurization processes. The base structure should be capable of accommodating increased internal pressure experienced during pasteurization; capable of accommodating vacuum formed in the sealed container during cool down; capable of resisting unwanted inversion or like deformation; and capable of efficient stacking with like containers.
With the foregoing in mind, a primary object of the present invention is to provide a commercially satisfactory wide-mouth blow-molded container that can be utilized in hot-fill applications as well as pasteurization, or retort, applications for packaging fluent, viscous and solid food products.
Another object of the present invention is to provide a base structure capable of accommodating an increase in internal container pressure when the sealed container is subjected to thermal treatment and capable of accommodating vacuum during cool down.
Still another object of the present invention is to provide a hot-fillable and pasteurizable container having a base which accommodates changes in internal pressure and volume and which resists unwanted inversion and other deformation.
A further object of the present invention is to provide a structure for a wide-mouth plastic container which can be efficiently stacked, one on top of the other, with like containers and which can be produced by means of high speed manufacturing equipment in an economical manner that ensures consistent quality and performance.
More specifically, the present invention provides a multi-functional base for a blow molded plastic container. The base has a discontinuous concave outer annular wall with an outer portion and an inner portion forming a standing ring therebetween. The base also includes an inner annular wall which extends inwardly and upwardly from the inner portion of the outer annular wall and which has an inner periphery and an outer periphery. The outer periphery of the inner annular wall has a plurality of radial webs extending outwardly at an elevation above the standing ring, and the inner periphery of the inner annular wall connects to an anti-inverting, upwardly-projecting dome. Functionally, the inner annular wall is capable of flexing upwardly and downwardly in response to variations in pressures in a filled and sealed container without undergoing unwanted permanent deformation. In addition, preferably a shoulder extends radially inward on the inner portion of the outer annular wall above a level of the standing ring to facilitate vertical stacking of containers having like bases.